n.
Pronunciation: ' tä- ˌ n ō , t ə - ' n ō
Function: noun
Inflected Form: plural tonneaus
Etymology: F, literally, tun, from Old French tonel ― more at TUNNEL
Date: 1901
1 : the rear seating compartment of an automobile also : the entire seating compartment
2 : a shape of watch case or dial resembling a barrel in profile